The present invention is related to intrusion detection systems and more specifically involves a system for both detecting intruders and for presenting signals to the intruders to deter them from further depth of intrusion.
Many detection systems including alarms and automatic locking systems are disclosed in the prior art. These systems are directed solely toward the objective of detecting an intrusion after the fact and generating an alarm to some point distant from the intrusion. None of the conventional devices has as a primary function the prevention of further intrusion by the burglar or unwanted visitor. Most of the prior art devices available today consist of what is known as "perimeter systems". The typical perimeter system comprises a ring of detection devices around an area such as a home or business providing a single line of defense. Usually these detection devices comprise switches connected to a central alarm system to indicate to the occupants that the perimeter system has been violated. The disadvantages of this system are severe. One such disadvantage is that the system gives no warning until the intruder has penetrated the protected area. At this time a relatively defenseless homeowner may be faced with an armed intruder bent on committing crimes of burglary, or worse, within the homestead. Another disadvantage is that once this type of system is tripped, it cannot reset unless all switches happen to return to their normal state. One example of a typical perimeter system alarm is that disclosed in U.S. Pat. No. 4,206,450 to Harden, et al. This patent discloses a perimeter fire and burglar alarm system having a series of sensors wired around the perimeter utilizing timers to allow the time of the alarm to be set or to allow the owner of the alarm to set the alarm and leave without tripping it. Once any one of the sensors is tripped by any of the expected events, such as intrusion or fire, the system immediately goes into the alarm mode, or else after a set time period goes into an alarm mode. This system can provide no further action with respect to the intrusion or fire. Thus, the Hardin patent discloses a standard perimeter alarm system adapted to provide a single alarm signal in response to a single sensed event.
Another example of a perimeter system providing a single alarm signal is that disclosed in the Burney patent, U.S Pat. No. 3,543,261. Burney discloses a single alarm system having a spacially separated set of sound detection sensors which are adjusted to avoid false alarms. Another example of a single alarm perimeter system is that disclosed in U.S. Pat. No. 4,385,287 to Eatwell. Although the sensors and the signaling apparatus are more sophisicated than that of conventional devices, the system is still a single alarm perimeter type system.
The patent to Boyko, U.S. Pat. No. 3,599,195, discloses a dual alarm intrusion detection system which utilizes motion sensors and heat/smoke detectors. The Boyko alarm utilizes only two alarms. One sensor can actuate both alarms. This system can detect intrusion only, or fire only, and has no sensor lockout, or capability for further detection after a sensor has been tripped. The patent to Ferrigno, U.S. Pat. No. 3,221,317, discloses a battery operated sensor system which senses moisture or other conditions and generates a sound signal through a public address system speaker. The patent is directed to a battery saving feature of this simple perimeter system. The system is intended to primarily convert natural phenomenon such as moisture or lightning, or changes in brightness, sound, voltage, current, and other natural phenomenon directly into electrical currents which then may be converted to audible signals. The patent to Forbat, U.S. Pat. No. 3,979,740, discloses a monitoring system which can be used as an intruder alarm. The system is primarily designed to prevent the generation of false alarms. The system is a perimeter system that has the capability of counting a number of intrusion pulses during a set period of time and then actuating a single alarm. The system has various means to filter out false signals. The system is limited in that once it has determined that an intrusion has occured it is limited in response to a single alarm.
U.S. Pat. No. 3,261,009 to Stetten, et al. is directed to a personnel sensing device utilizing seismic sensors. This system features filters for reducing false signals and utilizes timing circuits to respond only to a predetermined pattern of seismic signals. Once the system has determined or "recognized" the predetermined pattern, a single alarm is generated.
The patent to Galvin, U.S. Pat. No. 4,195,286, discloses a simple two stage system utilizing a single sensor to set off a first stage and two sensors to set off a second stage. The Galvin system requires both stages to go off almost simultaneously. The defect in this system is that the activation of a second stage at a spaced interval from the first stage will not provide the proper alarm response. Also if a single sensor is disabled no further capability is recognized in the system. The primary object of the Galvin system is to provide "overlapping coverage". The patent to Buckles, U.S. Pat. No. 3,900,841, discloses a purely mechanical system utilizing mechanical timers, gear systems, and screw drives. Also cams, switches, and motors are utilized. The Buckles system is slow to respond to multiple stimulations because of the mechanical drive. Also any sensor which is activated will continue to drive and actuate the entire system. It cannot be reset with any open or disabled sensor. The Buckles system is not satisfactory for an external perimeter system. It utilizes a "free period" when no alarm is given. Also the Buckles system lacks the ability to totally reset the timers because of its mechanical linkage. Also the system resets only if all sensors are in their normal position. Thus the Buckles system is a very inflexible unreliable system because of the purely mechanical timed actions of the system. Very little adjustment can be achieved with the Buckles intrusion system. The Buckles system also lacks the deterrent capabilities of the present invention.
All of the aforementioned conventional alarm systems suffer from the disadvantages that they generally rely upon a single, or at most, a double tripping of external sensors. They suffer from a further disadvantage that the alarm generated in response to the one or two sensors is a single alarm and usually occurs after the undesirable intrusion has occured. The conventional systems offer no deterrent capabilities for preventing the undesired intrusion. Furthermore the systems lack automatic resetting capabilities after one or more of the sensors have been tripped.